Optical fibers may be used in medical laser systems to deliver a laser energy to a treatment site. Many such optical fibers include a fiber core with a distal end surrounded by a cap. Some caps include a reflective surface configured to direct the laser energy away from the fiber core, and an air pocket distal of the reflective surface. Because most reflective surfaces cannot reflect all of the laser energy, the air pocket is often required to achieve total reflection of the laser energy. To accommodate the air gap, most caps typically have an outer diameter larger than an outer diameter of the fiber core, resulting in an enlarged bulbous shape at the distal end of the fiber. Most caps include an exit port for the laser energy. In some instances, the exit port may include a lens or other aperture that further increases the outer diameter of the cap, and/or creates other irregularities in the enlarged bulbous shape.
In some noninvasive medical procedures, a scope may be advanced through a body toward a body cavity, and the optical fiber may be advanced distally through a working channel of the scope until the cap is adjacent a target in the body cavity, such as a kidney stone in a kidney. The inner diameter of the working channel must be sized to accommodate the larger diameter and/or enlarged bulbous shape of the cap, thereby requiring a larger working channel. Irregularities of the enlarged bulbous shape may further increase the requisite size of the working channel. A larger channel may be undesirable, especially considering that most scopes include other working channels competing for a limited amount of space inside of the scope.
The optical fibers and associated laser systems described herein address these problems and other deficiencies in the prior art.